Tool

  1. dlvr.it
  2. Feedblitz
  3. Feedburner
  4. twitterfeed.com

 

WordPress Plugin

  1. http://wordpress.org/plugins/facebook/
  2. https://wordpress.org/plugins/wp-to-twitter/
  3. https://wordpress.org/plugins/twitter-auto-publish/
  4. https://wordpress.org/plugins/social-networks-auto-poster-facebook-twitter-g/
  5. https://wordpress.org/plugins/social-media-auto-publish/
  6. http://jetpack.me/support/publicize/
  7. http://www.nextscripts.com/social-networks-auto-poster-for-wordpress/